/* Define single-letter commands that will be sent by the PC over the
   serial link.
*/
void init_distance_of_ultrasonic();
void hc_sr04_pin_init();
//float trig_measure_of_a(unsigned char pin_num);
void get_the_real_distance_of_Ultrasonic(void);
void report_to_ros_of_Ultrasonic(void);

